As the power module industry has matured, commercially available dc-dc power converter modules have achieved widespread usage in many distributed power architectures commonly employed in networking and telecommunications equipment. At present, many systems have begun employing a combination of both isolated dc-dc power modules and point-of-load (POL) modules.
Before distributed power architectures with power modules were widely employed (so-called bulk-power supplies), isolated, multi-output power supplies were (and still are) used in many applications. These isolated, multi-output power supplies typically featured either multiple isolated power trains in one package or isolated power trains that had multiple outputs. In general, the power magnetics, especially the power transformers, were fairly complex, expensive, custom devices. If additional output voltages were required or the load was partitioned differently, a significant redesign effort would be required. Typically, the isolated designs featured relatively slow dynamic performance characteristics that were not well suited for driving lower voltage rails that are common in today's power systems.
The power module industry later began offering both single- and multi-output isolated power modules. FIG. 1 shows a typical prior art configuration that employs separate isolated modules 101-103 for each output voltage rail Vo1-Vo3. Customers select a brick module for each rail that is appropriate for their load. Although the solution generally works, the cost of using many isolated power modules is quite high due to the presence of many control circuits and power transformers, and similar to the earlier bulk-power supplies, the isolated module's performance is limited.
FIG. 2 shows an alternate prior art configuration that employs a single isolated power module 201 and multiple non-isolated Point of Load (POL) modules 211-213 downstream. The advantage of this configuration is that the POL modules 211-213 are much lower cost than an isolated module. If numerous rails are in the system, the customer may buy one relatively high power, expensive isolated module such as module 201 and use it to power several POL modules. However, this approach still requires the customer to buy multiple building block products and does not guarantee the system will be optimized for performance and cost or that it will even work properly when the building blocks are assembled together.
The manufacturers of commercially available power converters would prefer to sell one product family for use in many power systems. However, differences in system level requirements, such as cross-system compatibility is an ongoing challenge. Systems vary widely in terms of power levels, the number of voltage rails required, and sensitivity to cost and performance metrics such as transient response.
From the customer perspective, end users would prefer to specify a custom power system that is fine tuned to their application. However, the cost associated with a custom power system is generally prohibitive for most end users. Power supply manufacturers have responded by creating “building blocks” or families of brick modules that achieve relatively good cost structures by being usable by multiple customers and generally compatible from one brick to the next. Several standard footprints have been proposed by industry alliances with the goal of providing multi-sourcing options for end users.
While the prior art does offer a workable solution to power module users, it is not ideal. As explained above, customers must purchase several power modules, each with its own built-in labor and profit structure, instead of buying a single part. Furthermore, the building blocks may not be especially well tuned to the customer's application. The building blocks may have compatibility issues between them even when manufactured by the same supplier. Ensuring compatibility from multiple suppliers therefore becomes an even bigger problem to manage.
Customers frequently do not have detailed schematics or know how to optimize the performance of the power module system when the various components are put together. Therefore, they may end up adding excessively large and expensive capacitor banks to ensure system stability. Alternatively, customers may raise system cost by over specifying parameters such as the voltage regulation or ripple/noise requirements of the individual power modules in order to have the best chance of the system working once the various pieces are assembled together. To overcome these challenges power module manufacturers quite often wind up making semi-customized or modified versions of their standard products in order to work properly in the customer systems, thereby entailing the excessive cost structures they are attempting to avoid in the first place.